Method of insulation formation and application

ABSTRACT

The method of forming a lightweight, high performance, glass fiber blanket for acoustical and thermal insulation, that includes treating glass fibers with a fluid binding agent at elevated temperature to form a first cohesive glass fiber layer of thickness t 1  traveling endwise, and winding that layer into a roll above a travel zone of that layer, repeating said treating to form a second cohesive glass fiber layer of thickness t 2  traveling endwise over said zone below said roll and into an oven, and unrolling said first layer from said roll to travel into the oven in overlying surface to surface contacting relation to the traveling second layer, subjecting said layers to heat treatment and pressurization in the oven to compress the first and second layers to a controlled density thickness t 3  which is substantially less than t 1  and t 2 , and to progressively bond said first and second layers together in laminated relation to form the blanket, and removing said laminated product from the oven.

This application is a continuation-in-part of pending U.S. applicationSer. No. 10/340,889, filed Jan. 13, 2003.

BACKGROUND OF THE INVENTION

This invention relates generally to provision and use of a lightweight,high performance, glass fiber blanket employed in aircraft and marineapplications to provide thermal and acoustical insulation; and moreparticularly concerns an improved method of producing that blanket.

For many years aircraft original equipment manufacturers (OEMs) haveemployed a light weight, high performance, and special fiberglass forthermal and acoustical insulation. This insulation is typically 1 inch,0.42 pounds per cubic foot (pcf); 1 inch, 0.60 pcf; and ⅜ inch, 1.5 pcf.

The insulation is sold to the OEMs or their fabricators.

Typically, three layers of 1 inch material are stacked together andencapsulated in a light weight Mylar film. The finished blanket,approximately 3 inches thick, is installed in the aircraft by a seriesof plastic pins that penetrate the insulation and are then fastened tothe aircraft interior. Caps and washers are placed over the pins tosecure the aircraft blanket in place. During this process, theinsulation is often compressed. Because the 3 inch blanket is only 0.42pcf, it is relatively limp and requires several pins for sidewall andoverhead installations to prevent sagging.

There is need for an improved process and product which provides thefollowing advantages:

-   -   1. The fabricator only needs to handle one layer of material        instead of multiple layers.    -   2. Shipping and storage of material requires less space.    -   3. A density product is more rigid and could be fully or        partially friction fitted. This requires fewer pins for        application which, in turn, reduces installed weight per square        foot. This is the OEMs primary objective.    -   4. Requires less space in the interior of the aircraft for        insulation which is very critical in smaller regional aircraft.

SUMMARY OF THE INVENTION

It is a major object of the invention to provide a highly affective, andunusually advantageous process and product meeting the above needs.Basically the unusually advantageous method of forming the neededlightweight, high performance, glass fiber blanket for acoustical andthermal insulation, includes the steps:

-   -   a) treating glass fibers with a fluid bonding agent at elevated        temperature to form a first cohesive glass fiber layer of        thickness t₁ traveling endwise, and winding that layer into a        roll above a travel zone of that layer,    -   b) repeating said treating to form a second cohesive glass fiber        layer of thickness t₂ traveling endwise over said zone below        said roll and into an oven, and unrolling said first layer from        the roll to travel into the oven in overlying surface to surface        contacting relation to the traveling second layer,    -   c) subjecting said layers to heat treatment and pressurization        in the oven to compress the first and second layers to a        controlled higher density thickness t₃ which is substantially        less than t₁ and t₂, and progressively bonding said first and        second layers together in laminated relation to form the        blanket,    -   d) and removing the laminated product from the oven.

Typically, t₃ is between about 1 inch and 1½ inch, and has about 0.105pounds per square foot weight; and the weight per cubic foot of theproduct is one of the following:

-   -   i) 0.84    -   ii) 1.26.

As will be seen, the resultant blanket form product is highly useful inapplication as insulation for aircraft, as in fuselages for example, andthe method of installation includes the steps

-   -   i) installing the blanket as insulation to an aircraft wall        structure,    -   ii) and providing plastic retention pins, effecting penetration        of the pins through the blanket, and securing the pins to said        structure.

It is a further object to provide and operate endless conveyor means tocontact and convey the first and second layers through the oven; and toslit the produced, conveyor delivered laminated blanket into controlledwidth sections enabling direct installation into aircraft, as referredto.

These and other objects and advantages of the invention, as well as thedetails of an illustrative embodiment, will be more fully understoodfrom the following specification and drawings, in which:

DRAWING DESCRIPTION

FIG. 1 is a sectional view taken through overlying insulative blankets;

FIG. 2 is a view showing the two FIG. 1 blankets during reduction inthickness and bonding;

FIG. 3 is a section showing installation of the product compositeinsulation to aircraft structure; and

FIGS. 4 a and 4 b are elevations showing further details of productformation.

DETAILED DESCRIPTION

Referring first to FIG. 1, it shows two glass fiber layers 100 and 101extending in face-to-face relation at 102, and having thicknesses t₁ andt₂ which are preferably, but not necessarily the same. Each of thelayers 100 and 101 consists essentially of glass fibers generallyuniformly distributed in a resinous binder, which upon heating as inFIG. 2, becomes cured to bind the layers 100 and 101 together, atinterface 106.

The glass fibers in each layer typically have cross dimensions, as forexample diameters, between 2.0 and 9.0 HT, where HT=0.00001 inch. Thebulk of the glass fibers have lengths between 1 and 2 microns.

The total thickness t₁ and t₂ of the layers in FIG. 1 is preferablyabout 3 inches.

FIG. 2 is like FIG. 1, except that the layers are being compressed andheated in an oven between surfaces 104 and 105, and to reduced thicknesst₃. The resultant cured resinous bond between the layers is located at106.

The elevated curing temperature is typically about 425° F., for binderresin consisting of Phenol Formaldehyde, Melamine and/or otherthermal/set resins. Drying and curing at such elevated temperature ortemperatures is completed during a time interval between 2 and 4minutes. The layers are preferably traveled endwise through a curingoven 110 (see heating elements 111) for that purpose, and thereafter theproduct blanket is slit into strips, as may be required. The strips maythen be cut into sections for use in application to aircraft structuresuch as frames. See FIG. 3.

FIGS. 4 a and 4 b show the complete, flame attenuation process, withnumerals 1-22 applied to elements or steps of the process. Such numeralsidentify the following:

-   -   1. holding tanks for batch glass ingredients    -   2. batch weighing and mixing apparatus    -   3. batch transport apparatus    -   4. binder resin tank    -   5. batch holding tank, proximate furnace    -   6. apparatus to feed bath ingredients from tank 5 to furnace 7    -   7. furnace operated at or near 2450° F., for example    -   8. bushings (typically consisting of platinum and rhodium)        through which molten glass flows from furnace, at about 1750° F.    -   9. rolls to pull glass through bushings, to produce fibers    -   10. burners, for producing hot gas jets to melt the fibers, to        attenuate them into finer fibers displaced or blown rightwardly        (see U.S. Pat. No. 5,389,121) to mix with binder resin, sprayed        at 11    -   11. binder spray nozzles receiving binder pumped from 4    -   12. roll, feeding backer sheet to travel rightwardly on chain        conveyor 15, within enclosure 13 a, to support the homogenized        (mixed) glass fibers and binder resin, collecting at 13    -   13. homogenized mix collection    -   14. forming fans    -   15. chain conveyor    -   16. curing oven through which formed layers travel and laminate        (see layers 100 and 100 a, in FIG. 2)    -   17. slitters, to slit cured product into strips    -   18. choppers to cut strips to selected length    -   19. roll-up roll, for roll-up of product sheet as in FIG. 4 a.        FIG. 4 b shows unrolling of the rolled first sheet 100 onto        second sheet 101 being formed and fed to curing oven 16    -   20. furnace air pollution control and treating apparatus    -   21. oven gas pollution control and treating apparatus    -   22 a. roll of rolled up first (upper layer 100 (see FIG. 4 a)    -   22 a′. roll 22 a being unrolled (see FIG. 4 b) to feed layer 100        onto layer 101    -   23. laminated composite product traveling on conveyor 24 a,        toward slitters 17.

The resultant laminated blanket product indicated at 120 in FIG. 3 is inone layer, and typically replaces the need for three layers. Forexample, the density of the product is typically, but not limited to thefollowing:

-   -   0.84 pound per cubic foot (pcf) where t₃ is 1½ inches, or    -   1.26 pcf where t₃=1 inch.

In each of the above, the density of the original layers 100 and 101 is0.42 pcf (three inches total original thickness t₁ to t₂).

In each of the above the weight per square foot of the product is 0.105lbs.

Accordingly, the weight per square foot of the layer 100 unrolled fromthe base roll is 0.0525; and the weight per square foot of the layer 101being produced (in FIGS. 4 a and 4 b) is 0.0525.

The top oven conveyor is then set to 1½″. The base roll is unrolled ontop of the material being produced and both layers are fed into theoven. As both layers contain uncured resin, the two layers are laminatedinto one finished layer, being bonded by the resin being cured in theoven.

The finished product is then slit to the proper width and rolled.

FIG. 3 shows application of the composite product to aircraft frame orsupport structure 50, which may be metallic, as by fasteners at 51, toprotect structure 50. Note that the composite blanket is locallycompressed at 52, as by such fasteners. The composite itself is openlyexposed to aircraft interior zone 60. Sections 53 of the compositecompletely and openly cover selected areas defined by the frame. Thesections 53 may be installed in abutting edge-to-edge configuration, asat 54.

1. The method of forming a lightweight, high performance, glass fiberproduct blanket for acoustical and thermal insulation, that includes: a)treating glass fibers with a fluid binding agent at elevated temperatureto form a first cohesive glass fiber layer of thickness t₁ travelingendwise, and winding that layer into a roll above a travel zone of thatlayer, b) repeating said treating to form a second cohesive glass fiberlayer of thickness t₂ traveling endwise over said zone below said rolland into an oven, and unrolling said first layer from said roll totravel into the oven in overlying surface to surface contacting relationto the traveling second layer, c) subjecting said layers to heattreatment and pressurization in the oven to compress the first andsecond layers to a controlled density thickness t₃ which issubstantially less than t₁ and t₂, and to progressively bond said firstand second layers together in laminated relation to form the productblanket, d) and removing said laminated product from the oven.
 2. Themethod of claim 1 including slitting said laminated blanket intocontrolled width sections.
 3. The method of claim 1 wherein t₃ isbetween about 1 inch and 1½ inch, and having about 0.105 pounds persquare foot weight.
 4. The method of claim 3 wherein the weight percubic foot of the product is about one of the following: i) 0.84 ii)1.26.
 5. The method of clam 1 including providing and operating endlessconveyor means to contact and convey the first and second layers throughthe oven.
 6. The product blanket formed by the method of claim
 1. 7. Theproduct blanked formed by the method of claim
 3. 8. The product blanketformed by the method of claim
 4. 9. The method of using the productblanket of claim 1, that includes: i) installing the blanket asinsulation to an aircraft or marine wall structure, ii) and providingplastic retention pins, effecting penetration of the pins through theblanket, and securing the pins to said structure.
 10. The method ofclaim 1 wherein the bonding agent is a phenolic resin sprayed into afalling stream of said glass fibers.